I just purchased an Arduino Uno after reading a bunch about it. Very excited about being a part of this.

I am, however, struggling with the first step! The orange LED on the board lights and flashes. When I upload to it, the TX/RX LEDs flash too so I have connectivity. When I stick an LED in gnd and 13... nothing happens with the LED. The LEDs are clearly rubbish, but I didn't really know that when I picked them up. They don't have an obvious longer/shorter leg either. I have tried a few of them (pack of 10) and still nothing. Could it really be that all the LEDs are dead? Could there be something wrong with the pins on the board? Could they be the "wrong kind" of LED as they have no longer/shorter leg?

LED's are polarised. They need to be connected the right way round to work. Plugging one into GND & pin 13 is not a good idea on an arduino made in the last 5 years (including the Uno). There is no current limiting resister in circuit. Its completely unnecessary any way, any arduino made in the last 5 years (The Uno) will have one on board, already wired and working. Its usually labelled 'L'. The tutorial you've found is out of date and doing it today can damage the Arduino. You may have already damaged the output on Pin 13.

LED's are polarised. They need to be connected the right way round to work. Plugging one into GND & pin 13 is not a good idea on an arduino made in the last 5 years (including the Uno). There is no current limiting resister in circuit. Its completely unnecessary any way, any arduino made in the last 5 years (The Uno) will have one on board, already wired and working. Its usually labelled 'L'. The tutorial you've found is out of date and doing it today can damage the Arduino. You may have already damaged the output on Pin 13.

Further delving, I realise now what I did wrong. Though I won't do it again, I was curious as to why even if you shouldn't do it (and believe me I won't do it again based on your advice) why it was working on a couple of the tutorials and not for me.

The tutorial on this site has you connecting the longer leg of the LED to a resistor, but as you say, not really necessary anyway. To be honest, the breadboard I bought doesn't correlate with the tutorials (only one ... power bit? where the tutorials all have two) and I got impatient. An unfortunate trait of mine... I'll buy a new breadboard tomorrow and make a start on more of the tuts.